.tooltip {
    position: absolute;
    bottom: 120%;
    left: 50%;
    transform: translateX(-50%);
    background: rgba(0,0,0,0.8);/* 修改背景颜色 */
    color: white;/* 修改文字颜色 */
    padding: 12px;
    border-radius: 6px;
    font-size: 12px;/* 调整字号 */
    line-height: 1.4;
    width: 220px;/* 调整最大宽度 */
    box-shadow: 0 3px 6px rgba(0,0,0,0.16); /* 添加阴影 */
    text-align: left;
    opacity: 0;
    visibility: hidden;
    transition: all 0.2s;
    z-index: 1000;
    pointer-events: none;
}

.tooltip::after {
    content: "";
    position: absolute;
    top: 100%;
    left: 50%;
    margin-left: -5px;
    border-width: 5px;
    border-style: solid;
    border-color: rgba(0,0,0,0.8) transparent transparent transparent;
}

.nav-item:hover .tooltip {
    opacity: 1;
    visibility: visible;
    transition-delay: 0.3s; /* 悬停0.3秒后显示 */
}
/* 响应式优化（移动端显示） */
@media (max-width: 768px) {
    .tooltip {
        width: 180px;
        font-size: 11px;
    }
}